Point-source nodes are the non-dimensional incarnations of the Holtzman Effect. They have no physical existence but do occupy definite locations.
The nodes had been discovered since the suspensor-nullification effect and were used to relocate the effect. Debate had raged as to how it's possible for something with no dimensions to interact in real space. Arguments have ranged from metaphysical claims that the node "knows" when it is invoked, to involved mathematical theories that claim that the node does exist, in a spacetime "pocket" of no volume.
A node is the "seed" of any other HE incarnation, originally of the suspensor-nullification which was first known; when a HE incarnation is discontinued, it collapses into a point-source HE node. This can be achieved either by discontinuing the maintenance power in which case the microlasers must reengage instantly or the point-source will wander and be lost. It's also possible to overload the field with an enormous amount of electrical energy to be grounded into it, which then collapses into the seed, and then is lost.
Nodes can be caged and transported in devices known as Laser Pens.
Then its location can be moved by gentle application of probability alterations. The effect then can be triggered back into existence in the new location, and be exactly the same as before and electrical power is fed into the field from any source providing the necessary energy such are microbatteries for Defensive Shields
- Dune Encyclopedia, entry HOLTZMAN EFFECT